Multiple capillary biochemical analyzer

ABSTRACT

A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibres to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands.

FEDERAL RIGHTS IN THE INVENTION

The U.S. Government has rights in this invention pursuant to Grant No.DE-FG02-92ER61123 awarded by the U.S. Department of Energy.

FIELD OF THE INVENTION

This invention relates to apparatus used for biochemical analysis.

BACKGROUND AND SUMMARY OF THE INVENTION

Simultaneous analysis of a large number of biological samples is usefulin flow cytometry, DNA sequencing, liquid chromatography,oligonucleotide analysis, zone electrophoresis of proteins, as well asother electrophoretic techniques. In particular, rapid DNA analysis isof importance in the Human Genome Project, which is an attempt toidentify the sequence of bases (dideoxynucleotides) in human DNA.

One technique that has been applied to the sequencing of DNA iscapillary electrophoresis. In capillary electrophoresis, an appropriatesolution is polymerized or gelled to form a porous matrix in a fusedsilica capillary tube of internal dimensions in the order of 50 μm. Anelectric field is applied across the matrix. Fragments of sample DNAinjected into one end of the capillary tube migrate through the matrixunder the effect of the electric field at speeds that depend on thelength of the fragment. Hence, different length fragments arrive at adetection part of the capillary at different times. Thedideoxynucleotide at one end of the fragment may be labelled with afluorescent marker during a reaction step. The fluorescent marker isassociated with the terminating dideoxynucleotide. When the fragmentpasses through a beam of light from a laser in the detection zone, thefluorescent marker fluoresces and the fluorescence may be detected as anelectric signal. The intensity of the electric signal depends on theamount of fluorescent marker present in the matrix in the detectionzone. The dideoxynucleotide at the end of the fragment may then beidentified by a variety of methods. As different length fragmentsmigrate through the matrix under the applied field, a profile of thefragments may be obtained.

The use of three different DNA sequencing techniques is set out inSwerdlow, H. et al, Three DNA Sequencing Methods Using Capillary GelElectrophoresis and Laser Induced Fluorescence., Anal. Chem., 53,2835-2841, Dec. 15, 1991, and the references cited therein. In the Taborand Richardson technique (one spectral channel sequencing), a singlefluorescent marker is used, and the amount of dideoxynucleotide in thereaction mixture is varied so that each base of the DNA fragment may beidentified with a particular fluorescent peak height. For example, theconcentration of dideoxynucleotides might be varied in the ratio of8:4:2:1. The variation in fluorescence intensity with time will thenidentify the sequence of bases. In the DuPont system (two spectralchannel sequencing), succinylfluorescein dyes are used to label fourdideoxynucleotides. A single wavelength (488 nm) is used to excitefluorescence from the dyes. Emission is distributed between two spectralchannels centered at 510 and 540 nm. The ratio of the fluorescentintensity in the two spectral channels is used to identify theterminating dideoxynucleotide. In the Applied Biosystems system (fourspectral channel sequencing), four dyes (FAM, JOE, TAMRA and ROX) areused to label primers to be used with each dideoxynucleotide reaction.Two lines from an argon laser (514.5 and 488 nm) are used to excitefluorescence. Interference filters are used to isolate emission at 540,560, 580 and 610 nm and peaks of the resulting four electrical signalprofiles are used to identify the bases.

Application of capillary electrophoresis to DNA analysis is complicatedby the scattering of light from the porous matrix and the capillarywalls. For this reason, there has been proposed use of a sheath flowcuvette in which a sample stream of DNA is injected under laminar flowconditions in the center of a surrounding sheath stream, generally ofthe same refractive index. Such a cuvette is described in Swerdlow H.,et al, Capillary Gel Electrophoresis for DNA Sequencing: Laser Inducedfluorescence detection with the sheath flow cuvette, Journal ofChromatography, 516, 1990, 61-67.

However, the above described methods of DNA sequencing using capillaryelectrophoresis have used single capillaries and rapid DNA sequencingand other biological process requiring simultaneous analysis of samplestreams require use of multiple capillary systems.

One such multiple capillary system is described in Huang et al,Capillary Array Electrophoresis Using Laser Excited ConfocalFluorescence Detection, Anal. Chem. 64, 967-972, Apr. 15, 1992. In theHuang device, multiple capillaries lying side by side in a flat arrayholder are sequentially scanned by a laser beam and fluorescencedetected from the capillaries using a photomultiplier tube. Such adevice suffers from the same difficulties as with a single capillarythat is scanned with a laser, namely that there is light scatter fromthe capillary walls and interfaces between the matrix and capillary.

The inventors have therefore proposed a multiple capillary analyzer thatallows detection of light from multiple capillaries with a reducednumber of interfaces through which light must pass in detecting lightemitted from a sample being analyzed.

In one aspect of the invention, there is provided a multiple capillaryanalyzer using a modified sheath flow cuvette. A linear array ofcapillaries is introduced into a rectangular flow chamber. Sheath fluiddraws individual sample streams through the cuvette. The capillaries areclosely and evenly spaced and held by a transparent retainer in a fixedposition in relation to an optical detection system. Collimated sampleexcitation radiation is applied simultaneously across the ends of thecapillaries in the retainer. Light emitted from the excited sample isdetected by the optical detection system.

In a further aspect of the invention, the retainer is provided by atransparent chamber having inward slanting end walls. The capillariesare wedged into the chamber. One sideways dimension of the chamber isequal to the diameter of the capillaries and one end to end dimensionvaries from, at the top of the chamber, slightly greater than the sum ofthe diameters of the capillaries to, at the bottom of the chamber,slightly smaller than the sum of the diameters of the capillaries.

In a still further aspect of the invention, the optical system utilizesoptic fibres to deliver light to individual photodetectors, one for eachcapillary tube. A filter or wavelength division demultiplexer may beused for isolating fluorescence at particular bands.

In a still further aspect of the invention, the array may berectangular, including square, or the like formed of plural rows ofcapillaries terminating at different levels in a rectangular sheath flowcuvette. A rectangular array of lenses receives light emitted, scatteredor reflected from samples emerging from the capillaries and the light isthen converted to electrical signals and processed.

BRIEF DESCRIPTION OF THE DRAWINGS

There will now be described a preferred embodiment of the invention,with reference to the drawings, by way of illustration, in which likenumerals denote like elements and in which:

FIG. 1 is an isometric schematic view of an exemplary biochemicalanalyzer according to the invention showing a sheath flow cuvette,multiple capillaries, a flow chamber and optical system;

FIG. 2 is a section through the analyzer of FIG. 1 without opticalcomponents;

FIG. 3A is a section through the chamber of FIG. 1 showing the passageof a laser beam through the chamber;

FIG. 3B is a schematic showing a light collection and detection systemfor used with the analyzer of FIG. 2;

FIG. 4 is a section through the multicapillary sheath flow cuvette ofFIG. 2 (the section is through the center but also shows pedestals,which are off center, and appear behind the chamber);

FIG. 5 is a section at right angles to the section of FIG. 4 (thesection is through the center but also shows pedestals, which are offcenter, and appear behind the chamber);

FIG. 6 is a section along the line 6--6 in FIG. 5 showing the inlet forsheath fluid;

FIG. 7 is a section along the line 7--7 in FIG. 5 showing the off centerpedestals that retain the flow chamber;

FIG. 8 is a section along the line 8--8 in FIG. 4 showing the base ofthe cuvette;

FIG. 9 is a section along the line 9--9 in FIG. 4 showing a split rodwith a slot along its central axis for retaining the capillary tubes;

FIG. 10A is section through the top of the sheath flow cuvette;

FIG. 10B is longitudinal section through the sheath flow cuvette;

FIG. 10C is a section through the bottom of the sheath flow cuvette;

FIGS. 11A, 11B and 11C are graphs showing the results of DNA sequencingusing apparatus according to the invention;

FIG. 12 shows a schematic of a further method of detecting analyte;

FIG. 13 shows an apparatus for use for the electrochemical detection ofanalyte;

FIG. 14 is a schematic section of an analyzer having a rectangular (inthis case square) array in a square flow chamber;

FIG. 15 is a schematic view from the bottom of the chamber of FIG. 14;and

FIG. 16 is an isometric view of a square grid of capillaries forinsertion in the chamber of FIG. 14.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, there is shown an analyzer for analyzing asample of DNA including a sheath flow cuvette 12 enclosing the ends offive capillary tubes 14 arrayed side by side in a line like the teeth ofa comb. The capillary tubes 14 are held in a header 16 with theircleaved ends 18 terminating inside the chamber 12. The other ends 20 ofthe capillary tubes 14 terminate in five of the wells 22 of aconventional microtiter plate 24. The capillary tubes 14 areconventional fused silica capillaries, with about 50 μm ID and 150 μmOD, available from Polymicro. The cuvette 12 is formed of a quartzchamber 26 secured within a stainless steel holder 28, the design ofwhich is shown in FIGS. 4-9 in more detail. A high voltage source 30,such as a Spellman RHR-30PN60 30 KV power supply, is connected to thestainless steel holder 28 through a first electrode 32 (grounded) andalso through five second electrodes 34 to fluid in the wells 22. Thus,when the capillary tubes 14 and chamber 12 are filled with conductingmaterial, a high voltage may be applied across the material in thecapillary tubes using the high voltage source 30. The circuit is formedby the grounded electrode 32, the stainless steel holder 28 (formed ofcap 68, capillary retainer 64, chamber retainer 66 and cap 70), fluid inthe cuvette 12 and in the chamber 26, matrix in the capillary tubes,including sample buffer if present, buffer solution in the wells 22 andthe electrodes 34.

A laser 36 or other source of collimated electromagnetic radiationprovides a collimated beam 38 of light that is aligned to pass through afocusing lens 40 into the chamber 12 along a projection of the capillarytubes into the chamber, as close as possible to the ends of thecapillary tubes 14, as shown in FIG. 3A. The wavelength of the laser 36is chosen to excite fluorescence in the sample being analyzed, as forexample DNA reacted with a fluorophor. An appropriate choice for DNAanalysis is an Innova 70-4 argon ion laser available from Coherent Inc.of Palo Alto, Calif. Such a laser may be operated with multiplewavelength mirrors (488 and 514.5 nm), with appropriate selection of thewavelength depending on the method used for sequencing the DNA.

Fluorescence from the sample in the chamber 12 is detected through acollection lens 42 that images the fluorescence on to a plurality of 1mm aperture GRIN (gradient index) lenses 44 (available from NiponScientific Glass through Precision Cells, Inc. of Farmingdale, N.Y.)which are affixed to receiving ends 46 of fiber optics 48. The fibreoptics 48 may be secured in known manner as for example to a MellesGriot optical bread board (not shown). Transmitting ends 50 of the fiberoptics 48 lead into avalanche photodiodes 52 or other individual photondetectors, one for each capillary tube 14, and whose output is connectedthrough an interface 54 to a computer 56. Exemplary photodiodes 48 areRCA (EG&G) C309028 photodiodes powered by a PS310 Stanford ResearchSystem high voltage power supply or model SPCM 100 photodiodes availablefrom EG&G Canada Ltd., Fluorescence is transmitted along the fiberoptics 48 to the photodiodes 52 whose electrical output is proportionalto the intensity of the fluorescence. Electrical signals output from thephotodiodes 52 are passed through a data acquisition board 54 (such asmay be obtained from National Instruments or from Data Translation,model DT2221-G) to a computer 56 such as a Macintosh II computer forprocessing according to known techniques. Such processing includesfiltering the signal to give a desired frequency response, and a secondfilter or phase lock loop to identify the position of the peak centers.For interface boards from National Instruments, it may be necessary todecrease illumination intensity to avoid over saturation of the photondetectors. Alternatively, light collected in individual GRIN lenses 44may be passed through a bundle of optical fibres and imaged onto orabutted against an array detector. However, CCD cameras are not believedto be fast enough for high speed DNA sequencing.

As shown in FIGS. 3A and 3B, if the fluorescence emitted from the DNAsample has a spectrum centered on more than one wavelength of light,then a means of dividing the spectrum of the received light may be used.Light from laser 36 passes through focusing optic 40 and passes throughthe sample streams 58. Fluorescence from the sample streams is collectedby optic 42 and passed through a spectral filter 60 (for filteringscattered light) to GRIN lenses 44 on the ends of fibre optics 48. Lightin the fibre optics 48 is passed through wavelength divisiondemultiplexers 62 where light from different spectral bands is separatedinto two sets 48a and 48b of fibre optics and two sets of avalanchephotodiodes 52a and 52b.

The selection of the filter 60 and the optical system depends on thesequencing reaction to be performed. For a single codor sequencer, usingthe sequencing method of Richardson-Tabor, a single spectral filter 60with a bandwidth of 45 nm centered at 530 nm may be used to detectfluorescein labeled products. The filter should be selected to minimizebackground signals due to Raman and Raleigh scatter of the excitationbeam 38. For the DuPont sequencing system, two detection channels arerequired, one detector channel to image light in a band centered at 510nm and the other to image light centered at 540 nm. Light collected fromthe collection optic is split into two paths using the wavelengthdivision demultiplexers 62, one path leading to one set of photondetectors 52a and the other leading to the other set of photon detectors52b. Other methods of wavelength division demultiplexing may be used asfor example rapidly switching a filter wheel so that the light from thesample stream is time division demultiplexed For sequencing using themethod developed by Applied Biosystems Inc. (see the Swerdlow article),four channels are required. As with the DuPont system, two detectorsystems are used, and a filter wheel may be used as the spectral filter60 to rotate two selected filters across the path of the light collectedby the collection optic. By alternating the two filters in the twodetection systems, a signal from four spectral channels may begenerated.

The collection optic 42 should be selected to provide an image that ismatched in size to the aperture of the GRIN lenses 44, such as may beprovided by a flat field high numerical aperture microscope objective,for example as made by Leitz/Wild (0.40 NA achromat objective). With asample stream diameter of 50 μm and a GRIN lens diameter of 1 mm, forexample, the magnification should be about 20×, generating spots severalmillimeters apart. Since the light from the collection optic tends toexpand with a curved wavefront, the GRIN lenses should be arranged tohave their collection faces perpendicular to radii of the wavefront.

Referring to FIGS. 4-9, the chamber 26 is held in a stainless steelholder 28 to form a sheath flow cuvette. The holder 28 includes an uppersection or capillary retainer 64 and a lower section or chamber retainer66 each machined from individual pieces of steel rod. The retainers 64and 66 are threaded together at 65 (threads not shown). A top cap 68 isthreaded onto the upper end of retainer 64. A bottom cap 70 is threadedonto the lower end of retainer 66. An upper seal 72 made of plasticforms a seal between the cap 68 and retainer 64. A like seal (not shown)may be used to seal the cap 70 to the retainer 66. An O-ring (not shown)or other suitable seal should be provided to ensure that the retainers64, 66 are sealed together to prevent leakage at 65. The cap 68 has acentral hole for receiving the capillary tubes 14. A plastic sleeve 74into which the capillaries are threaded has epoxy applied to it to forma seal around the capillary tubes 14 as they enter the cap 68. Thecapillary retainer 64 includes a hollow bore lined with a plasticcylindrical and annular spacer 76. Filling out the hollow bore of theretainer 64 are two facing semi-circular metal rods 78 each with agroove machined into their facing flat faces to form a rectangular slot80. The slot 80 is dimensioned to receive the capillaries 14 snugly andhold them against each other in a line.

The chamber retainer 66 includes two circular sections 82 and 84 and apedestal section 86 in which the metal of the rod has been machined awayto form four pedestals 88 in which the chamber 26 is securely retained.Metal in the chamber retainer 66 is machined away in the pedestalsection 86 to form cavities 89. Removal of the metal in this section 86allows a microscope objective to be placed close to the chamber 26(within a few millimetres). Upper circular section 82 includes a sheathfluid inlet 90 and a bubble removal port 92. The sheath fluid inlet 90is connected via Teflon™ tubing 94 (see FIG. 2) to a source of sheathfluid 96 (not shown to scale). The bubble removal port 92 is connectedby Teflon™ tubing 98 to a valve 100. The tubing 94 may include a threeway valve 102 with waste line 104 for removing bubbles from the sheathfluid. In the chamber retainer 66, at the base of the chamber 26 is aplastic bottom plug 106 that holds the chamber 26 in place. The cap 70is provided with a waste outlet port 108 that is connected to Teflon™tubing 110 to a waste beaker 112.

As shown in FIG. 2, sheath fluid is provided through inlet 90. Thesheath fluid enters the top of the chamber 26 and moves as a syphon flowunder gravity from the top of the chamber to the bottom, past the ends18 of the capillary tubes 14. The fluid should be provided in a steady,non-pulsed flow, and should be filtered and purified to avoid anybackground signal passing due to particles passing through field of viewof the collection optics. The fluid is chosen to have similar index ofrefraction as the fluid carrying the sample DNA to avoid reflection andrefraction at interfaces between fluids of different indexes ofrefraction. The simplest way to achieve this is to use the same fluidfor the sheath fluid as carries the sample DNA, as for example 1xTBE.The volumetric flow of the sheath stream is low, in the order of lessthan 10 mL/hr, which for the embodiment described is in the order of 4mm/s, though it may be as much as 10× less for some applications. Thefluid is drained to waste after exiting the chamber 12 through port 108.The waste beaker 112 should be kept half-filled with buffer. If thewaste stream forms drops, the sample stream profile is distorted whenthe drop detaches. A periodic noise results from the periodic detachmentof the drops. The beaker 112 preferably has a small hole drilled in itwith a tube leading to a larger beaker 114. The level of the firstbeaker 112 remains constant, so that the sheath flow velocity underconditions of syphon flow changes slowly. A constant syphon head mayalso assist in ensuring constant sheath flow rate. For the apparatusdescribed a 5 cm syphon head has been found adequate. Bubbles should notbe present in the sheath flow. These can be eliminated by visualinspection and eliminated using the three way valve 102 (by switchingthe fluid containing the bubble to waste).

Referring to FIGS. 10a, 10b and 10c, the chamber 26 includes end walls122a, 122b, side walls 124a, 124b top 126 and bottom 128. The walls neednot be planar but may contain projections to align the capillaries. Eachwall is 1 mm thick at the top and made of high quality optical quartz,or such other inert material as is transparent to the selectedelectromagnetic radiation emitted by either the laser 36 or the samplepassing out of the capillary tubes 14. The side walls 124a, 124b areconstant thickness from top to bottom, while the end walls each thickeninward towards the bottom by 50μm. The interior of 130 of the chamber 26has the same dimension X laterally as the thickness of the capillarytube used (150 μm in the exemplary embodiment) and the dimension Y₁ fromend wall to end wall a little more (50 μm more in the exemplaryembodiment) than the sum of the thicknesses of the capillary tubes 14.The interior 132 at the bottom of the chamber has the same dimension Xlaterally as the thickness of the capillaries used and the dimension Y₂from end wall to end wall a little less (50 μm in the exemplaryembodiment) than the sum of the thicknesses of the capillary tubes 14.The capillary tubes 14 should be snugly fit in the interior of thechamber 26, with their ends terminating adjacent each other. It ispreferable that the capillary tubes 14 be placed in the chamber 26before they are filled with matrix material.

Particularly if capillary tubes are re-used, the collection optics,including the GRIN lenses 44, will be fixed and the capillary tubes 14must be aligned with the collection optic so that fluorescence from thesample stream irradiated by the laser beam 38 is imaged onto the GRINlenses 44. The capillary tubes 14 are first inserted through the cap 68and retainer 64 into the slot 80 formed by the two rods 78. Thecapillary tubes 14 may be loaded together or one by one. The capillarytubes 14 are inserted into the chamber 26 in this manner and pushedtogether into the chamber 26 until they are firmly held in the chamber26. With the chamber 26 of the dimensions stated, the capillary tubes 14will terminate about half way through the chamber 26. The top of thechamber 26 thus encompasses the capillary tubes 14 with the capillarytubes 14 abutting the interior walls of the chamber at the ends near thecenter of the chamber and at the sides throughout the length of thecapillary tubes within the chamber 26. Abutment of the capillary tubesagainst the interior walls of the chamber seals any gaps between thecapillary tubes at the center of the chamber 26. Unless such gaps aresealed, non-uniformities in the sheath flow can result which can affectthe signal quality. The capillary tubes 14 are preferably cleaved attheir ends using well known techniques employed in the manufacture offiber optics in order to obtain a smooth and flat end. The capillarytubes 14 will therefore extend into the interior of the chamber 26 anamount that is dependent on the rate of decrease of the end wall to endwall dimension of the chamber, and will typically be 1 cm for theexemplary embodiment described. The chamber 26 has height H about 2 cmfrom top to bottom as shown in the example. Such chambers may bepurchased from Nipon Scientific Glass through Precision Cells, Inc. ofFarmingdale, N.Y., to order. The height H of the chamber is somewhatarbitrary, sufficient to allow both fixture of the capillary tubes andto allow the light beam to pass through the chamber below the capillaryends. 2 cm is chosen to allow addition of a second laser beam below thefirst if two lasers are used for analysis. The top of the side walls124a, 124b should be slightly bevelled to ease insertion of thecapillary tubes 14. The construction of the chamber is quite important,particularly when the capillary tubes are not electrically isolated fromthe high voltage applied across the porous matrix material in thecapillary tubes. If the capillary tubes are not isolated electrically,repulsive forces between them can create forces which if not evenlydistributed, can shatter the capillary tubes. The capillary tubes 14should therefore all be held securely in the chamber to prevent thesestresses from concentrating at one tube.

The capillary tubes 14 should terminate within about 10 μm from eachother. The laser beam 38 should entirely pass within about 100 μm fromthe ends of the capillary tubes. Careful alignment of the capillarytubes is required so that the image of the fluorescence falls directlyon the GRIN lenses. This can be checked by passing light backwardthrough the GRIN lenses. The light should pass through the sample streamexactly at the same point that fluorescence due to the laser beamoccurs. Visual inspection can be used to verify the correct alignment ofthe capillary tubes, with appropriate safety precautions due to the useof laser light.

The length of the flow cell (distance between the end walls 124a and124b) and the number of capillaries that can be detected in a singleflow cell are determined by the distance over which laser beam size canbe matched to the sample stream radius as it exits the capillary. Tooptimize sensitivity, the laser beam should be located as near aspossible to the ends of the capillaries to minimize effects of diffusionof the sample into the sheath fluid. The laser beam should thereforepass through the acceleration region of the sample flow. At this point,faster moving sheath fluid draws the sample fluid from the matrix. Sincethe entire cuvette is grounded (through electrode 32), there is verylittle electric field inside the cuvette, and the sample fluid is notdrawn by the electric field out of the capillaries. Thus it is thesheath flow that draws the sample fluid from the matrix in thecapillaries. As the sample fluid moves away from the end of thecapillary its cross-section contracts, and then expands due to diffusionof the sample fluid into the sheath fluid. The laser beam should passthrough a point above the point of maximum contraction, thus before thediffusion zone.

A single laser beam is aligned to be parallel with the long axis of thecuvette (end wall 122a to end wall 122b) simultaneously excitingfluorescence from each sample stream in turn. The size of the laser beamshould be selected to ensure similar illumination of each sample stream.With a lens (for example a microscope objective with 1× magnification)between the laser 36 and the chamber 26 a beam waist can be located inthe center of the chamber. The beam spot size at the center of thechamber should be equal to the sample stream diameter at that point.With 50 μm ID capillary tubes, this is about 50 μm. The beam diameterwill be larger in both directions away from this point, but with thisarrangement, the fluorescence is close to optimum.

For setting up the analyzer for DNA analysis, care must be taken as isknown for capillary electrophoresis. Thus, the matrix material must beselected for stability, for discrimination of longer base lengths andfor speed of sequencing. No one matrix is suitable for all applications.For DNA sequencing, a 0%C (non-cross-linked), 5-6%T acrylamide gel hasfound to be adequate and has the added advantage of low viscosity whichallows it to be readily replaced, without removal of the capillary tubes14 from the chamber 26. A proprietary gel, Long-Ranger™ from ATBiochemicals, has been found useful for applications using high voltagein the order of 800 V/cm, such as in diagnostic applications.Long-Ranger™ gel allows sequencing rates in the order of 200 bases in 3minutes with greater than 95% accuracy. 0%C gels provide sequencingrates in the order of 600 bases in two hours at 200 V/cm. Geltemperatures between 20° C. and 35° C. have been found to give goodresults.

The Long-Ranger gel is prepared within a 50 μm ID capillary bypolymerization of a carefully degassed 5% solution of Long-Ranger in a7M urea, 0.6 x TBE buffer. Polymerization is initiated with 0.4 partsper thousand (V/V) TEMED and 0.4 parts per thousand (W/V) ammoniumpersulphate. Such a gel is stable and may be used for three separations.Use of Long-Ranger gel with a single 50 μm ID capillary has yieldedsequencing rates of 3200 bases per hour at 800 V/cm.

The gel may include 0-20% of formamide. Addition of formamide in thisrange decreases compressions, particularly in the range 10-20%, therebyincreasing resolution in regions of compression. However, it has beenfound that too much (20% or more) formamide reduces the separation rate,theoretical plate count, and resolution for normally migrating fragmentswithout a concomitant decrease in compressions. An optimum concentrationof 10% formamide improves resolution of compressed regions withoutdegrading other characteristics of the gel. It has also been found thatoperating the gel at room temperature is adequate and simplifies theengineering of the analyzer. Results of using formamide have beendescribed in Rocheleau, M. J., et al, Electrophoresis, 13, 484-486,1992.

The gel should be established in the capillary tubes 14 without voids orbubbles forming during polymerization of the acrylamide due toshrinkage, which may be particularly acute if a bifunctional silanereagent is used to bind the gel to the capillary wall. Such bubbles canbe eliminated by use of low percent acrylamide, short columns, addingpolyethylene glycol to the monomer mixture (though this is not desiredfor DNA fragments longer than about 100 bases since it degrades theseparation) or by allowing polymerization to occur in a pressured vesselor other methods known in the art.

Also, defects in the gel at the ends 20 may occur when loading samplesof DNA into the capillary tubes 14. Such defects are particularly ofconcern when the capillary tubes 14 are reused. It is thereforedesirable to cut off a portion (several millimetres) of the capillarytube 14 after a run. Also, such a defect can be minimized by loadingsmaller amounts of DNA sample, as much as five times lower, as comparedwith conventional electrophoresis sequencing of DNA. Thus for examplethe sample using the apparatus disclosed should be loaded at 150 V/cmfor 60 s.

Flaws in the gel can be inspected by visual inspection in a microscopeor by passing two laser light beams at an angle through the gel tointersect each other in the gel. Modulated light scatter of the laserlight from flaws in the gel may be detected using a collection optic andphotomultiplier tube.

Loading of the gel into the capillary tubes 14 also requires care. It isdesirable that gel characteristics be uniform from capillary tube tocapillary tube. If the capillary tubes are loaded with gel sequentially,differences in the gel may severely degrade the analysis. It ispreferable to load the gel monomer into a single container and to fillthe capillaries with the gel from the single container simultaneously,as by vacuum syphoning the gel. At high electric fields (in the order of800 V/cm), the gel can extrude about 50 μm from the detection end of thecapillary. To eliminate extrusion, about 2 cm of the gel at thedetection end is covalently bonded to the interior walls of thecapillary tubes with γ-methacryloxypropyltrimethoxysilance. Such knownmethods for establishing a gel as described in U.S. Pat. Nos. 4,865,706and 4,865,707 to Karger et al and 4,810,456 to Bente et al may also beused.

Data has been collected from the system of FIG. 1 with detection atthree capillaries using the Tabor and Richardson sequencing technique.An M13mp18 template was used to generate fragments of DNA. Manganese wasused instead of magnesium in the sequencing buffer. Sequenase was usedfor chain extension. A FAM labeled primer is used and a singlesequencing reaction is performed with ddATP, ddCTP, ddGTP and ddTTPpresent in a 8:4:2:1 ratio. A 50 μm capillary was filled with 4%T, 5%Cgel and operated at 200 V/cm. For a run of 330 bases in 70 minutes,comparable data was obtained as for single capillary systems, althoughthe throughput was 850 bases/hour for a 3 capillary system. FIGS. 11a,11b and 11c show the results of the sequencing.

Resolution is limited to fragments less than 300 bases in length at highvoltages near 800 V/cm. Generally speaking, retention time increaseslinearly with fragment length for a given high V/cm until the mobilityof the fragments approaches a limiting value and no separation isachieved. This is called biased reptation. As the electric fieldincreases, the transition to biased reptation moves to shorterfragments. Biased reptation is highly undesirable since it causessequencing fragments to coelute, destroying the separation resolution.Hence for longer fragments (in the order of 600 bases), the electricfield can be decreased to about 140 V/cm, with an increase in separationtime. Moderate gel temperature (in the order of 20° to 35° C.) canassist in improving sequencing rate, though it does not appear tostrongly affect the transition from reptation to biased reptation. Lower%T acrylamide gels can also assist in the sequencing of longerfragments.

The analyzer described here has utility for a wide variety ofapplications, with some modifications. In each case there is some meansto force analyte through the capillaries, the capillaries are held inthe chamber as shown in FIG. 1 and 2 for example, and sheath fluid issupplied through the cuvette, with the sheath fluid preferably havingthe same index of refraction as the fluid carrying the analyte.

The detection of analyte may also be accomplished using thermoopticalabsorption. In this technique, the laser 36 is used to excite theanalyte which tends to heat the analyte and change the index ofrefraction of the fluid by which it is carried. As shown in FIG. 12, thedeflection of the beams 138 from a second laser 136 after collimatingwith an appropriate optic 137 by the sample fluid emerging from the endsof the capillary tubes 14 is then detected by the optical system 140,which may be designed as shown in FIG. 1.

An analyzer for use as an electrochemical detector is shown in FIG. 13.Electrodes 142 enter the chamber 26 (made of an inert non-conductingmaterial such as quartz) from the bottom end 132 of the chamber. Eachelectrode 142 is connected to an amplifier (not shown), and the outputof the amplifier is provided to a processor, for example a computer,through an interface for analysis in accordance with known principles(similar to the optical processing of the signals). In such a case, thelaser 36 is not required, since the identification of the sample is byelectrochemical analysis. Multiple capillaries allow for rapid analysis.

The analyzer may also be used to detect impurities in fluids bydetecting light scatter. In such a case, the high voltage source 30 isnot required, since the fluid may be pumped directly as a fluid throughthe capillary tubes, nor is the spectral filter 60 required since thetotal intensity of the scattered light may be detected. The GRIN lenses44 and detectors 52 detect variations in the scatter of light resultingfrom particles or impurities in the fluid.

The analyzer is also useful for the detection of organic contaminants,for example the fluorescent detection of polycyclic aromatichydrocarbons. In such detection, the capillary tubes are filled withchromatographic packing material (coated silica beads) instead of apolymer and the analyte sample is forced through the capillary tubesusing a pump instead of the high voltage source 30. The laser 36 shouldemit radiation at about 330 nm or such other appropriate wavelength fordetection of organic contaminants. Fluorescence emitted by the sample ofcontaminant is detected through an appropriate spectral filter 60 andthe optical apparatus shown for example in FIG. 1.

In a further example, the analyzer may be used for flow cytometry. Inflow cytometry a sample containing cells taken from an animal or humanbody by fine needle aspiration is stained using a fluorescent reagentsuch as a nucleic acid stain or antibodies. With the present analyzer,the sample is forced under air pressure by a pump that replaces the highvoltage source 30 through the capillary tubes 26 and the laser beam 38is passed through the sample as it emerges from the capillary tubes 26into the sheath flow. The intensity of the fluorescence from thefluorescent reagent is detected using the optical system of FIG. 1 andused to estimate the number of sets of chromosomes in the cells, andthis is useful, in accordance with known procedures in the diagnosis andprognosis of cancer.

Multiple capillary tubes may also be used to spray analyte into a massspectrometer. In such a case, the capillaries are bundled within acircular or polyhedral cuvette with sheath flow about the capillaries.The bundle of capillaries is inserted into the ionization chamber of amass spectrometer such as the triple quadrupole mass spectrometer soldby Sciex Division of MDS Health Group Limited, of Thornhill, Ontario,Canada, under its trademark TAGA 6000E. For electrospray of analyte, thecapillary tubes are made conducting at the end that extends into theionization chamber. Electrical potential is applied to the ends of thecapillaries in known manner.

A square, rectangular or other suitable polyhedral array of capillarytubes may also be used as well, as shown in FIGS. 14, 15 and 16 for thecase of a square capillary array. The array may be rectangular as well.Other polyhedral arrays could be used in principal, but this complicatesthe optics. The array of capillary tubes 14 is formed from five rows 144of five capillary tubes 14 each, all bound within a square chamber 146forming part of a square sheath flow cuvette. The cuvette is similar tothe cuvette shown in FIGS. 4-9 only the central chamber is square. Anoptical system 148 disposed adjacent the cuvette includes a collectionoptic 154, GRIN lenses 156, and optic fibres 158 leading to photodiodesand the balance of the optical system as shown in FIG. 1.

Each row 144 of capillary tubes is similar to the row shown in FIG. 1,but succeeding rows in the direction of the optical system 148 terminatehigher in the sheath flow cuvette as shown at 160. All capillary tubes14 in a row terminate adjacent each other. Sheath flow is provided aboutall of the tubes 14 within the sheath flow cuvette. All four walls 150of the sheath flow cuvette taper inward towards the bottom 152 of thechamber. The ends of the capillary tubes 14 define a sloping plane P,sloping downward and away from the optical system 148. An elliptical orother linear cross-section laser beam 162 oriented at the same slope asthe sloping plane (or close to it) is directed just below the ends ofthe capillary tubes 14. Fluorescence of the samples forms a slopingsquare array of fluorescent spots 164 that appears as a square grid ofspots 166 from a view at right angles to the cuvette.

Fluorescence from sample streams emerging from the capillary tubes 14 iscollected by an optic 154 and imaged on to the square array of GRINlenses 156, which lie in the image plane of the fluorescent spotsproduced by the optic 154. The GRIN lenses 156 are oriented with theirfaces perpendicular to the wavefront from the collection optic 154.Light collected by the GRIN lenses is transmitted through optic fibresto photodetectors of the type shown in FIG. 1.

It is possible to operate the cuvette upside down to allow bubbles inthe sheath stream to move upward with the stream to waste.

A person skilled in the art could make immaterial modifications to theinvention described and claimed in this patent document withoutdeparting from the essence of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An analyzer foranalyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondsends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in said capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; an electrophoretic voltage sourceconnected across said capillary tubes to force said organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes, said flow chamber being heldessentially at ground potential; a detector positioned to detect organicsample in the individual sample streams emerging from the capillarytubes; and an outlet for draining said sheath flow fluid and entrainedstreams directly from said flow chamber to waste, said outlet having asubstantially larger flow area than said capillary tubes to therebypermit non-capillary flow therethrough.
 2. An analyzer for analyzing anorganic sample, the analyzer comprising:a plurality of capillary tubesarrayed side by side, each capillary tube having first and second ends,the second ends of the capillary tubes terminating adjacent each otherand the first ends being connectable to a source of organic sample; aflow chamber having an interior cavity, the seconds ends of thecapillary tubes terminating inside the interior cavity; means to supplysheath fluid into the interior cavity of said flow chamber to provide aflow of sheath fluid past the second ends of the capillary tubes suchthat any organic sample in said capillary tubes is drawn by the flow ofsheath fluid in individual sample streams from the second ends of thecapillary tubes; an electrophoretic voltage source to force said organicsample through the capillary tubes from the first ends of the capillarytubes to the second ends of the capillary tubes; said electrophoreticvoltage source being connected across the length of the capillary tubeswhereby said flow chamber is held essentially at ground potential; and adetector positioned to detect organic sample in the individual samplestreams emerging from the capillary tubes.
 3. An analyzer for analyzingan organic sample, the analyzer comprising:a plurality of capillarytubes arrayed side by side, each capillary tube having first and secondends, the second ends of the capillary tubes terminating adjacent eachother and the first ends being connectable to a source of organicsample; a flow chamber having an interior cavity, the seconds ends ofthe capillary tubes terminating inside the interior cavity; means tosupply sheath fluid into the interior cavity of said flow chamber toprovide a flow of sheath fluid past the second ends of the capillarytubes such that any organic sample in said capillary tubes is drawn bythe flow of sheath fluid in individual sample streams from the secondends of the capillary tubes; means to force said organic sample throughthe capillary tubes from the first ends of the capillary tubes to thesecond ends of the capillary tubes; a detector positioned to detectorganic sample in the individual sample streams emerging from thecapillary tubes; an exit port in said flow chamber for draining saidsheath flow fluid and entrained streams directly from said flow chamberto waste, said exit port having a substantially larger flow area thansaid capillary tubes to thereby permit non-capillary flow therethrough;and means to prevent drop formation at said exit port.
 4. An analyzerfor analyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondsends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in said capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; means to force said organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes; said means including anelectrophoretic voltage source connected across the length of thecapillary tubes; a detector positioned to detect organic sample in theindividual sample streams emerging from the capillary tubes; an exitport in said flow chamber for drawing sheath fluid from said chamber;and means to prevent drop formation at said exit port.
 5. An analyzerfor analyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondsends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in said capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; means to force said organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes; a detector positioned todetect organic sample in the individual sample streams emerging from thecapillary tubes, said detector being selected from the group comprisingthermo-optical absorption detectors and electrochemical detectors; andan outlet for draining said sheath flow fluid and entrained streamsdirectly from said flow chamber to waste, said outlet having asubstantially larger flow area than said capillary tubes to therebypermit non-capillary flow therethrough.
 6. An analyzer for analyzing anorganic sample, the analyzer comprising:a plurality of capillary tubesarrayed side by side, each capillary tube having first and second ends,the second ends of the capillary tubes terminating adjacent each otherand the first ends being connectable to a source of organic sample; aflow chamber having an interior cavity, the seconds ends of thecapillary tubes terminating inside the interior cavity; means to supplysheath fluid into the interior cavity of said flow chamber to provide aflow of sheath fluid past the second ends of the capillary tubes suchthat any organic sample in said capillary tubes is drawn by the flow ofsheath fluid in individual sample streams from the second ends of thecapillary tubes; means to force said organic sample through thecapillary tubes from the first ends of the capillary tubes to the secondends of the capillary tubes; said means including an electrophoreticvoltage source connected across the length of the capillary tubes; and adetector positioned to detect organic sample in the individual samplestreams emerging from the capillary tubes, said detector being selectedfrom the group comprising thermo-optical absorption detectors andelectrochemical detectors.
 7. An analyzer for analyzing an organicsample, the analyzer comprising:a plurality of capillary tubes arrayedside by side, each capillary tube having first and second ends, thesecond ends of the capillary tubes terminating adjacent each other andthe first ends being connectable to a source of organic sample; a flowchamber having an interior cavity, the seconds ends of the capillarytubes terminating inside the interior cavity; means to supply sheathfluid into the interior cavity of said flow chamber to provide a flow ofsheath fluid past the second ends of the capillary tubes such that anyorganic sample in said capillary tubes is drawn by the flow of sheathfluid in individual sample streams from the second ends of the capillarytubes; means to force said organic sample through the capillary tubesfrom the first ends of the capillary tubes to the second ends of thecapillary tubes, said means to force being selected from the groupcomprising pumps and gas pressure; a detector positioned to detectorganic sample in the individual sample streams emerging from thecapillary tubes; and an outlet for draining said sheath flow fluid andentrained streams directly from said flow chamber to waste, said outlethaving a flow area substantially larger than that of the capillary tubesto thereby permit non-capillary flow therethrough.
 8. An analyzer foranalyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondsends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in said capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; means to force said organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes; a detector positioned todetect organic sample in the individual sample streams emerging from thecapillary tubes; an outlet for draining said sheath flow fluid andentrained streams directly from said flow chamber to waste, said outlethaving a flow area substantially larger than that of the capillary tubesto thereby permit non-capillary flow therethrough; and wherein saidplurality of capillary tubes is arranged in a two-dimensional array andwherein said detector comprises a mass spectrometer having an ionizationchamber, the second ends of said capillary tubes being disposed withinsaid ionization chamber.
 9. An analyzer for analyzing an organic sample,the analyzer comprising:a plurality of capillary tubes arrayed side byside, each capillary tube having first and second ends, the second endsof the capillary tubes terminating adjacent each other and the firstends being connectable to a source of organic sample; a flow chamberhaving an interior cavity, the seconds ends of the capillary tubesterminating inside the interior cavity; means to supply sheath fluidinto the interior cavity of said flow chamber to provide a flow ofsheath fluid past the second ends of the capillary tubes such that anyorganic sample in said capillary tubes is drawn by the flow of sheathfluid in individual sample streams from the second ends of the capillarytubes; means to force said organic sample through the capillary tubesfrom the first ends of the capillary tubes to the second ends of thecapillary tubes; said means including an electrophoretic voltage sourceconnected across the length of the capillary tubes; a detectorpositioned to detect organic sample in the individual sample streamsemerging from the capillary tubes; and wherein said plurality ofcapillary tubes is arranged in a two-dimensional array and wherein saiddetector comprises a mass spectrometer having an ionization chamber, thesecond ends of said capillary tubes being disposed within saidionization chamber.
 10. An analyzer for analyzing an organic sample, theanalyzer comprising:a plurality of capillary tubes arrayed side by side,each capillary tube having first and second ends, the second ends of thecapillary tubes terminating adjacent to and abutting each other and thefirst ends being connectable to a source of organic sample; a flowchamber having an interior cavity, the second ends of the capillarytubes terminating inside the interior cavity; means to supply sheathfluid into the interior cavity of said flow chamber to provide a flow ofsheath fluid past the second ends of the capillary tubes such thatorganic sample from the capillary tubes is drawn by the flow of sheathfluid in individual sample streams from the second ends of the capillarytubes; means to force organic sample through the capillary tubes fromthe first ends of the capillary tubes to the second ends of thecapillary tubes; and a detector to detect organic sample emerging in theindividual sample streams from the capillary tubes.
 11. The analyzeraccording to claim 10, wherein the detector includes a source ofcollimated electromagnetic radiation having a wavelength that may excitethe sample to emit radiation, said source being aligned to providecollimated light through the organic sample drawn from the capillarytubes by the sheath fluid.
 12. The analyzer of claim 11 in which thedetector includes an optical system aligned to receive emitted radiationfrom the organic sample.
 13. The analyzer according to any one of claims1 or 2, wherein said flow chamber is at ground potential.
 14. Theanalyzer according to claim 13, wherein said chamber is at leastpartially formed of a transparent material and includes a recessedportion wherein the transparent material is exposed; and wherein saiddetector includes a source of collimated radiation and means forreceiving emitted radiation from said sample streams; and wherein saidsource of collimated radiation and means for receiving emitted radiationare positioned in said recessed portion and adjacent to said transparentmaterial.
 15. The analyzer of claim 11 in which the detector is anoptical system that receives scattered radiation from contaminantscarried by the sample.
 16. The analyzer of claim 11, in which saidcapillary tubes are arrayed in a linear array.
 17. The analyzer of claim11 in which the chamber includes an upper portion and a lower portion,and the means to supply sheath fluid includes a tube connected to theupper portion of the chamber, and the lower portion of the chamberencircles the second ends of the capillary tubes.
 18. The analyzeraccording to claim 12, wherein a least a portion of the lower portion ofthe chamber is made of transparent material, said portion being adjacentthe second ends of the capillary tubes.
 19. The apparatus according toclaims 17, wherein said detector further comprises a source ofcollimated electromagnetic radiation for generating electromagneticradiation in a first direction which is generally orthogonal withrespect to the direction of flow of said sample streams and an opticalcollection means positioned to receive radiation emitted from saidsample streams in a second direction which is generally orthogonal withrespect to the direction of flow of said sample streams.
 20. Theanalyzer according to claim 10, wherein the means to force the organicsample through the capillary tubes includes an electrophoretic voltagesource connected across the length of the capillary tubes.
 21. Theanalyzer according to claim 10, wherein said capillary tubes are arrayedin a linear array.
 22. The analyzer according to claim 10, wherein themeans to supply sheath flow into said interior cavity includes areservoir of sheath fluid syphon coupled to the chamber.
 23. Theanalyzer according to claim 10, wherein said flow chamber comprises aside wall at least partially encircling said interior cavity and whereinat least a segment of the side wall is transparent to electromagneticradiation radiating away from organic sample drawn from the capillarytubes by the sheath fluid.
 24. The apparatus according to claim 23,wherein said detector further comprises a source of collimatedelectromagnetic radiation for generating electromagnetic radiation in afirst direction which is generally orthogonal with respect to thedirection of flow of said sample streams and an optical collection meanspositioned to receive radiation emitted from said sample streams in asecond direction which is generally orthogonal with respect to thedirection of flow of said sample streams.
 25. The analyzer according toclaim 10, wherein said chamber comprises a side wall at least partiallyencircling said interior cavity and wherein at least a segment of theside wall is transparent to electromagnetic radiation radiating awayfrom organic sample drawn from the capillary tubes by the sheath fluidand in which at least a further segment of the side wall is transparentto the collimated electromagnetic radiation.
 26. The apparatus accordingto claim 25, wherein said detector further comprises a source ofcollimated electromagnetic radiation for generating electromagneticradiation in a first direction which is generally orthogonal withrespect to the direction of flow of said sample streams and an opticalcollection means positioned to receive radiation emitted from saidsample streams in a second direction which is generally orthogonal withrespect to the direction of flow of said sample streams.
 27. Theanalyzer according to claim 10, wherein each of said capillary tubes hasan inside diameter on the order of about 50 μm and an outside diameteron the order of about 150 μm.
 28. The analyzer according to claim 10,wherein said means to force an organic sample through the capillary tubecomprises an electrophoretic voltage source of on the order of 30 kvconnected across said capillary tubes and said flow chamber.
 29. Theanalyzer according to claim 10, wherein the organic material is carriedin said capillaries by a fluid, said fluid having essentially the sameindex of refraction as the sheath fluid.
 30. The analyzer according toclaim 10, wherein the volumetric flow of sheath fluid through saidchamber is on the order of less than about 10 mL/hr.
 31. The analyzeraccording to claim 10, wherein the rate flow of sheath fluid throughsaid chamber is on the order of less than about 4 mm/sec.
 32. Theanalyzer according to claim 10, further comprising an exit port in saidflow chamber for drawing sheath fluid from said chamber and means toprevent drop formation at said exit port.
 33. The analyzer according toany one of claim 3 or 4, wherein said means to prevent drop formationcomprises a container, at least partially filled with fluid, connectedto said exit port and into which the fluid from said chamber drains. 34.The analyzer according to claim 10, wherein said detector comprises athermo-optical absorption detector.
 35. The analyzer according to anyone of claims 34, 6 or 7, wherein said organic samples are carried insaid capillary tubes in a fluid and said detector comprises:a firstlaser, aligned with said array of capillary tubes for simultaneouslyexciting the organic samples in said individual sample streams and forheating said fluid; a second laser for passing a laser beam through eachof said individual sample streams in a direction generally orthogonal tothe direction of alignment of said first laser; and an optical systemfor receiving emitted light from said individual sample streams.
 36. Theanalyzer according to claim 10, wherein said detector comprises anelectrochemical detector.
 37. The analyzer according to any one ofclaims 36, 5 or 6, wherein said chamber is made of an inert,non-conducting material and further comprising an array of electrodesaligned with said array of capillary tubes and disposed in said chamberdownstream, in the direction of sheath fluid flow from the second endsof said capillary tubes;means, connected to each of said electrodes, forelectrochemically analyzing each of said individual sample streams. 38.The analyzer according to claim 10, wherein said means for forcing theorganic sample through said capillary tubes comprises a pump.
 39. Theanalyzer according to claim 10, wherein the means to force the organicsamples through the capillary tubes comprises gas pressure.
 40. Theanalyzer according to claim 10, wherein said plurality of capillarytubes is arranged in a two-dimensional array and wherein said detectorcomprises a mass spectrometer having an ionization chamber, the secondends of said capillary tubes being disposed within said ionizationchamber.
 41. The analyzer according to any one of claims 40, 8 or 9,wherein a portion of the second capillary tubes extends into saidionization chamber, said portion being formed of an electricallyconductive material.
 42. The analyzer according to claim 10, whereinsaid plurality of capillary tubes are arranged side by side-in abuttingrelationship.
 43. The analyzer according to claim 11, wherein a fluidacceleration region is formed downstream of the second ends of saidcapillaries, and wherein said source of collimated electromagneticradiation is positioned to direct said radiation at the fluidacceleration region.
 44. The apparatus according to claim 11, whereinsaid detector further comprises an optical collection means positionedto collect radiation emitted by said sample in a direction generallyorthogonal to the direction of flow of said sample streams.
 45. Ananalyzer for analyzing an organic sample, the analyzer comprising:aplurality of capillary tubes arrayed side by side, each capillary tubehaving first and second ends, the second ends of the capillary tubesterminating adjacent each other and the first ends being connectable toa source a flow chamber having an interior cavity, the seconds ends ofthe capillary tubes terminating inside the interior cavity; means tosupply sheath fluid into the interior cavity of said flow chamber toprovide a flow of sheath fluid past the second ends of the capillarytubes such that any organic sample in said capillary tubes is drawn bythe flow of sheath fluid in individual sample streams from the secondends of the capillary tubes; means to force said organic sample throughthe capillary tubes from the first ends of the capillary tubes to thesecond ends of the capillary tubes; and a detector, including a sourceof collimated electromagnetic radiation having a wavelength that mayexcite the sample to emit radiation to detect organic sample emerging inthe individual sample streams from the capillary tubes; said sourcebeing aligned to provide collimated light through the organic sampledrawn from the capillary tubes by the sheath fluid, said detectorfurther comprising an optical system aligned to receive emittedradiation from the organic sample, said optical system including pluralphotodetectors, one for each capillary tube.
 46. An analyzer foranalyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in said capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; means to force the organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes; and a detector including afirst source of collimated electromagnetic radiation having a wavelengththat may excite the sample to emit radiation to detect organic sampleemerging in the individual sample streams from the capillary tubes, saidsource being aligned to provide collimated light through organic sampledrawn from the capillary tubes by the sheath fluid, said detectorfurther comprising a second source of collimated electromagneticradiation aligned to direct a beam of radiation at each of said samplestreams, further comprising an optical system aligned to detectradiation from said sample streams.
 47. An analyzer for analyzing anorganic sample, the analyzer comprising:a plurality of capillary tubesarrayed side by side, each capillary tube having first and second ends,the second ends of the capillary tubes terminating adjacent each otherand the first ends being connectable to a source of organic sample; aflow chamber having an interior cavity, the second ends of the capillarytubes terminating inside the interior cavity; means to supply sheathfluid into the interior cavity of said flow chamber to provide a flow ofsheath fluid past the second ends of the capillary tubes such that anyorganic sample in said capillary tubes is drawn by the flow of sheathfluid in individual sample streams from the second ends of the capillarytubes; means to force the organic sample through the capillary tubesfrom the first ends of the capillary tubes to the second ends of thecapillary tubes; a detector including a source of collimatedelectromagnetic radiation having a wavelength that may excite the sampleto emit radiation to detect organic sample emerging in the individualsample streams from the capillary tubes; said source being aligned toprovide collimated light through the organic sample drawn from thecapillary tubes by the sheath fluid; and wherein the means to forcesample through the capillary tubes comprises a pump and the capillarytubes are filled with chromatographic packing material.
 48. An analyzerfor analyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity, the secondends of the capillary tubes terminating inside the interior cavity;means to supply sheath fluid into the interior cavity of said flowchamber to provide a flow of sheath fluid past the second ends of thecapillary tubes such that any organic sample in the capillary tubes isdrawn by the flow of sheath fluid in individual sample streams from thesecond ends of the capillary tubes; means to force organic samplethrough the capillary tubes from the first ends of the capillary tubesto the second ends of the capillary tubes; a detector to detect organicsample emerging in the individual sample streams from the capillarytubes; and wherein said plurality of capillary tubes are arrayed in atwo-dimensional array formed of plural rows of capillary tubes, each rowof capillary tubes terminating at a different level from any other rowof capillary tubes.
 49. An analyzer for analyzing an organic sample, theanalyzer comprising:a plurality of capillary tubes arrayed side by side,each capillary tube having first and second ends, the second ends of thecapillary tubes terminating adjacent each other and the first ends beingconnectable to a source of organic sample; a flow chamber having aninterior cavity, the second ends of the capillary tubes terminatinginside the interior cavity; means to supply sheath fluid into theinterior cavity of said flow chamber to provide a flow of sheath fluidpast the second ends of the capillary tubes such that any organic samplein the capillary tubes is drawn by the flow of sheath fluid inindividual sample streams from the second ends of the capillary tubes;means to force organic sample through the capillary tubes from the firstends of the capillary tubes to the second ends of the capillary tubes; adetector, including a source of collimated electromagnetic radiationhaving a wavelength that may excite the sample to emit radiation todetect organic sample emerging in the individual sample streams from thecapillary tubes, said source being aligned to provide collimated lightthrough the organic sample drawn from the capillary tubes by the sheathfluid, and; wherein said capillary tubes are arrayed in atwo-dimensional array formed of plural rows of capillary tubes, each rowof capillary tubes terminating at a different level from any other rowof capillary tubes.
 50. An analyzer for analyzing an organic sample, theanalyzer comprising:a plurality of capillary tubes arrayed side by side,each capillary tube having first and second ends, the second ends of thecapillary tubes terminating adjacent each other and the first ends beingconnectable to a source of organic sample; a flow chamber having aninterior cavity, the second ends of the capillary tubes terminatinginside the interior cavity; means to supply sheath fluid into theinterior cavity of said flow chamber to provide a flow of sheath fluidpast the second ends of the capillary tubes such that any organic samplein the capillary tubes is drawn by the flow of sheath fluid inindividual sample streams from the second ends of the capillary tubes;means to force organic sample through the capillary tubes from the firstends of the capillary tubes to the second ends of the capillary tubes; adetector, including a source of collimated electromagnetic radiationhaving a wavelength that may excite the sample to emit radiation todetect organic sample emerging in the individual sample streams from thecapillary tubes, said source being aligned to provide collimated lightthrough the organic sample drawn from the capillary tubes by the sheathfluid, and; wherein said means to supply sheath fluid includes: areservoir of sheath fluid; a sheath fluid supply tube connected betweenthe reservoir and the chamber; and means to prevent bubbles in thesheath fluid supply tube from entering into the chamber.
 51. Theanalyzer of claim 45 in which the optical system includes a collectionlens aligned to provide an image to the photodetectors.
 52. The analyzeraccording to claim 13, further comprising an electrically conductiveholder for holding said flow chamber.
 53. The analyzer according toclaim 52, wherein said electrically conductive holder is effective tominimize the electric field within the flow chamber whereby the organicsample is drawn from the capillary by said flow of sheath fluid.
 54. Theapparatus according to any one of claims 45, 46, 47 or 49, wherein saiddetector further comprises an optical collection means positioned tocollect radiation emitted by said sample in a direction generallyorthogonal to the direction of flow of said sample streams.
 55. Theapparatus according to claims 48, wherein said detector furthercomprises a source of collimated electromagnetic radiation forgenerating electromagnetic radiation in a first direction which isgenerally orthogonal with respect to the direction of flow of saidsample streams and an optical collection means positioned to receiveradiation emitted from said sample streams in a second direction whichis generally orthogonal with respect to the direction of flow of saidsample streams.
 56. The analyzer of claim 48 in which the array is arectangular array.
 57. The analyzer according to claim 48, wherein saiddetector comprises an optical detection system including an opticalcollection means having an axis of orientation and wherein the secondends of the capillary tubes define a sloping plane within the interiorcavity of said flow chamber, said sloping plane being inclined withrespect to the axis of orientation of said optical collection means. 58.The analyzer according to claim 57, wherein said detector furthercomprises a source of collimated electromagnetic radiation for emittinga beam of collimated electromagnetic radiation having a generally linearcrosssection, a major axis of said cross-section being aligned with saidsloping plane.
 59. The apparatus according to claims 57 or 58, whereinsaid generally linear cross-section is elliptical.
 60. An analyzer foranalyzing an organic sample, the analyzer comprising:a plurality ofcapillary tubes arrayed side by side, each capillary tube having firstand second ends, the second ends of the capillary tubes terminatingadjacent each other and the first ends being connectable to a source oforganic sample; a flow chamber having an interior cavity and a side wallencircling the interior cavity, the second ends of the capillary tubesterminating inside the interior cavity; means to supply sheath fluidbetween the side wall and the capillary tubes to provide a flow ofsheath fluid past the second ends of the capillary tubes such that anyorganic sample in the capillary tubes is drawn by the flow of sheathfluid in individual sample streams from the second ends of the capillarytubes; means to force organic sample through the capillary tubes fromthe first ends of the capillary tubes to the second ends of thecapillary tubes; a detector to detect organic sample emerging in theindividual sample streams form the capillary tubes; and wherein theencircling side wall including wall portions which taper towards eachother from a separation that is greater than the sum of the capillarytube diameters to a separation that is less than the sum of thecapillary tube diameters.
 61. The analyzer according to claim 10,wherein said means to force an organic sample through the capillarytubes comprises an electrophoretic voltage source connected across saidcapillary tubes and said flow chamber whereby the sheath flow in saidflow chamber is held at essentially ground potential.
 62. The analyzeraccording to claim 12, in which the optical detection system furthercomprises a wave length division demultiplexer for separating emittedradiation into light of at least two spectral bands, and at least twophotodetectors for each capillary tube, one for each of said spectralbands.
 63. The analyzer according to claim 49, wherein said detectorfurther comprises an optical detection system including an opticalcollection means having an axis of orientation and wherein the secondends of the capillary tubes define a sloping plane within the interiorcavity of said flow chamber, said sloping plane being inclined withrespect to the axis of orientation of said optical collection means, andwherein said source of collimated electromagnetic radiation has agenerally linear crosssection, a major axis of said cross-section beingaligned with said sloping plane.